The present disclosure relates generally to an open air, wide area noise cancellation system and method. More particularly, the present disclosure relates to a system and method for improved identification and characterization of noise sources including identifying locations and predicted paths of moving noise sources and then generating noise cancelling sound waves based on the detected locations and predicted paths of the noise sources.
As cities continue to grow, environmental noise pollution has become an increasing problem for the location of homes and businesses. Airports, highways, construction sites, and factories are common noise producing sources located near homes and businesses.
Noise blocking walls are often built between roads and nearby houses. However, it is not practical to build sound blocking walls to block off all homes and businesses from noise producing sources. The wide area noise cancellation system and method of the present disclosure provides improved noise cancellation without requiring the use of such noise blocking walls or other sound blocking structures.
As air traffic continues to increase and cities continue to grow, homes and businesses are often located near airports. At the same time, the size of aircraft continues to increase leading to greater noise pollution. Public complaints often lead to restrictions being imposed on flight paths and operation hours for airports. Often, residential development may be prohibited or restricted in areas surrounding the airport flight paths. The system and method of the present disclosure reduces the impact of noise pollution within areas located near common noise sources, such as airports. Therefore, the present system and method may allow use of property close to airports (or other noise sources) without requiring substantial usage restrictions.
While one embodiment of the present disclosure is particularly useful in areas surrounding airports, other embodiments may be used in other areas such as near construction sites, sporting venues such as automobile race tracks, factories or adjacent highways. In one embodiment, the open air noise cancellation system of the present disclosure is used in areas surrounding a military base or other noise producing area to substantially reduce or cancel noises occurring on the base from being heard outside a base perimeter. This reduces the likelihood that persons located outside the base perimeter will hear operations occurring inside the military base.
In one illustrated embodiment of the present disclosure, a wide area noise cancellation system is provided for reducing the effect of noise generated by at least one noise source within a noise producing area at locations outside the noise producing area. The system includes a plurality of spaced apart microphone arrays positioned within the noise producing area. Each microphone array detects noise from at least one noise source located in the noise producing area and generates an output signal indicative of the detected noise. The system also includes a noise signal processor configured to receive the output signals from the plurality of microphone arrays. The processor processes the output signals to determine noise cancellation signals to reduce the effect of noise from the at least one noise source. The system further includes a plurality of speaker arrays located at spaced apart locations around a periphery of the noise producing area. The plurality of speaker arrays receive the noise cancellation signals from the processor and generate inverse sound waves to reduce the effect of the noise from the at least one noise source before the noise from exits the noise producing area.
In one illustrated embodiment, the plurality of microphone arrays are spaced apart around a perimeter of noise producing area, and the plurality of speaker arrays are spaced apart around the perimeter of noise producing area at locations radially outwardly from the locations of the plurality of microphone arrays. Illustratively, the noise producing area is a military base, a construction site, or a factory.
In another illustrated embodiment of the present disclosure, a method is provided for reducing the effect of noise generated by at least one noise source within a noise producing area at locations outside the noise producing area. The method includes providing a plurality of speaker arrays located at spaced apart locations around a periphery of the noise producing area, detecting noise from the at least one noise source located in the noise producing area, determining noise cancellation signals based on the detected noise to reduce the effect of noise from the at least one noise source, and driving the plurality of speaker arrays with the noise cancellation signals to generate inverse sound waves to reduce the effect of the noise from the at least one noise source before the noise from exits the noise producing area.
In yet another illustrated embodiment of the present disclosure, a wide area noise cancellation system is provided for reducing the effect of noise generated by a noise source. The system includes at least one speaker array and at least one microphone array configured to detect noise from the noise source before the noise reaches the at least one speaker array. Each speaker array includes a plurality of speakers arranged to provide substantially 360° coverage for sound waves produced by the speaker array. Each microphone array generates an output signal indicative of the noise detected from the noise source. The system also includes a noise signal processor configured to receive the output signals from the at least one microphone array. The processor processes the output signals to determine a location of the noise source, to determine inverse sound waves based on the output signals, and to generate noise cancellation signals to drive the at least one speaker array so that the at least one speaker array genera s the inverse sound waves to reduce the effect of the detected noise from the noise source before the noise reaches the location of the at least one speaker array.
In an illustrated embodiment, the noise source is a moving noise source, and the processor determines the location and a predicted path of the moving noise source based on the output signals received from the at least one microphone array. The location and the predicted path of the moving noise source are used by the processor along with the output signals from the at least one microphone array to determine the inverse sound wave. In one illustrated embodiment, the processor adjusts a phase and a frequency of the inverse sound waves based on the location of the at least one speaker array relative to the location and the predicted path of the noise source.
In still another illustrated embodiment of the present disclosure, a method is provided for reducing the effect of noise generated by a noise source. The method includes providing at least one speaker array. Each speaker array includes a plurality of speakers arranged to provide substantially 360° coverage for sound waves produced by the speaker array. The method also includes detecting noise from the noise source before the noise reaches the at least one speaker array, determining a location of the noise source, generating noise cancellation signals based on the detected noise and the determined location of the noise source, and driving the at least one speaker array with the noise cancellation signals so that the at least one speaker array generates the inverse sound waves to reduce the effect of the detected noise from the noise source before the noise reaches the location of the at least one speaker array.
In one illustrated embodiment of the present disclosure, the method further includes generating calibration sound waves with the at least one speaker array, detecting the calibration sound waves, determining areas of sound interference within a noise cancellation area, and adjusting the noise cancellation signals based on the determined areas of sound interference within the noise cancellation area.
In another illustrated embodiment of the present disclosure, the method further includes generating and storing sound profiles from at least one known noise source, and adjusting the noise cancellation signals to generate the inverse sound waves based on the stored sound profiles from the at least one known noise source.
Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. The exemplification set out herein illustrates embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.